XYLARIA ROOTROT OF APPLE 1 
By Frederick A. WoEF, Plant Pathologist , and Richard O. Cromweee, Assistant 
Plant Pathologist , North Carolina Agricultural Experiment Station 
INTRODUCTION 
During the year 1913, specimens of diseased apple roots (Mains syl- 
vestris) were received for examination at the North Carolina Experiment 
Station. These roots were found to be invaded in a characteristic man¬ 
ner by a fungus, which was suspected of being the cause of death of the 
tree from which the specimens were taken. Identification of this organ¬ 
ism was impossible, since no fruit bodies could be found; but it was 
realized that the fungus exhibited points of difference from those ordi¬ 
narily recognized as the cause of apple rootrots. When, however, in 
the spring of 1914, other specimens of the same disease were received, 
the fungus was isolated in pure culture by the planted-plate method. 
Since this fungus was very evidently different in its cultural characters 
from familiar forms associated with the decay of apple roots and since no 
report of a similar disease could be found in the literature at hand, a 
study of the identity and pathogenicity of this organism was begun. A 
preliminary report, in abstract, 2 of this work has appeared under the title 
“Black rootrot of apple.” Investigations of this disease have been in 
progress more or less continuously for about three years, and it is deemed 
advisable to present at this time the data on hand relative to the distri¬ 
bution and symptoms of the disease and the identity, cultural characters, 
and pathogenicity of the causal organism. 
distribution of the disease 
It has been impossible thus far to make a careful survey in order to 
determine the exact distribution of this disease in North Carolina. Col¬ 
lections made by the junior author in 1914 show that the disease occurs 
in Haywood and Wilkes Counties. In addition, specimens were received 
during the same year from a correspondent in Polk County. During the 
following year the same disease was again collected in several localities 
in Wilkes County and also in the counties of Alexander, Surry, and 
Warren. In 1916, collections were made in Henderson County and from 
new localities in Wilkes and Haywood Counties. Since the places of col¬ 
lection are so widely separated and since no particular difficulty has been 
experienced in finding trees characteristically affected in any of the sec¬ 
tions devoted to apple growing, it is believed that this rootrot is generally 
1 Published with the permission of the director of the North Carolina Experiment Station. 
* Fulton, H. R., and Cromwell, R. O. Black rootrot of apple. (Abstract.) In Phytopathology, v. 6, 
no. x, p. no. 1916. 
Journal of Agricultural Research, 
Washington, D. C. 
ii 
(269) 
Vol. IX. No. 8 
May 21, 1917 
Key No. N. C. — 5 
